The ancient traditions of India are often described as ‘Sanatana Dharma’. Indians for a very long time recognized the significance of Water and use it in various rituals, particularly for the purification of the human body which is prone to sickness or illness attributed to sinful thoughts, words, and actions. The term ‘Theertham’ refers to water that is sanctified by prayerful thought and by using it in the devotional worship of God. The term ‘Tirtha’ refers to a body of water such as a well, pond, lake, river, or sea which gets an elevated status because of its geographical association with a physical location, place, or position named ‘Sthan’ or ‘Kshetra’. The physical journey to visit the place of Tirtha Sthan is called Tirtha Yatra. The act of taking a bath or dipping into the water at a Tirtha Sthan is called Tirtha Snaan.

I ask my readers to reflect on the divine attributes of the Water Molecule. The original, sweet taste of fresh water cannot be discovered by the study of the properties of the Chemical Elements, Hydrogen and Oxygen which combine to form the Chemical Compound called Water. Man, like several other terrestrial creatures, depends upon Fresh Water delivered from ‘Heaven’.

Millions of people have taken to the waters at the confluence of India’s sacred Ganges and Yamuna rivers as part of the Kumbh Mela festival – humanity’s largest gathering.

Officials told the BBC some 15m people bathed on Tuesday. They expect about 120m visitors over 49 days.

Hindus believe bathing at the rivers will cleanse their sins and bring salvation.

The holy men were among the first procession to arrive early Tuesday.

Sadhus – or ascetics – smeared ash on their bodies as they came out of the water and chanted “Har Har Gange”, or “Mother Ganges”, and danced while posing for photographers.

Image copyright Ankit Srinivas

The Naga sadhus are the biggest draw of the festival – held in the northern city of Allahabad, recently renamed Prayagraj – and arrived early in the morning in massive colorful processions.

Thousands of the Sadhus – naked and wearing marigold garlands around their necks – were escorted by police to the river as they chanted slogans invoking Shiva, the Hindu god of destruction. Many were waving tridents and swords.

At the last Kumbh in 2013, female ascetics were allowed to bathe at the confluence of the rivers – known as the Sangam – for the first time. A few hundred transgender people were among those who bathed on Tuesday morning.

More than a million foreign pilgrims will also take part in the festival, senior administration official Rajeev Rai told the BBC.

He and other organizers had been preparing for more than a year for the event, which dwarfs the annual Hajj pilgrimage to Islam’s holiest sites in Saudi Arabia.

The mela (meaning “fair” in Hindi) has been held in Allahabad for centuries now, but it has grown into a mega event in the past two decades.

Image copyright Getty Images

This year the gathering will be particularly huge and many believe India’s Hindu nationalist government has organized it with an eye on key general elections due in the summer.

Massive billboards of Prime Minister Narendra Modi dot Allahabad city and the Mela ground. Huge cardboard cut-outs have been placed strategically at the bathing areas.

Image copyright Ankit Srinivas

A temporary tent city spread over 32 sq km (12 sq miles) has been set up to accommodate the masses, complete with hundreds of kilometers of new roads. Hospitals, banks, and fire services have been set up just for the festival, along with 120,000 toilets.

Hundreds of new train services are running to and from Allahabad to tackle the rush of pilgrims and more than 30,000 police and paramilitaries have been deployed to provide security and manage the crowds.

In the run-up to the festival, religious sects held daily processions marked by much pomp and show.

Image copyright Ankit Srinivas

At one such procession on Sunday night, there were elephants, camels, and horses. Brass bands and drummers played, as religious leaders sitting atop several vehicles threw marigold flowers to thousands of devotees.

On Monday – a day before the official start of the festival – tens of thousands of pilgrims bathed at the Sangam. Some then lit clay lamps and floated them along with flowers in the Ganges.

Image copyright Ankit Srinivas

Image copyright Ankit Srinivas

The atmosphere at the mela is festive, and the authorities have announced a calendar of music and dance performances. But there’s plenty of impromptu entertainment taking place by the roadside, with children performing rope tricks and shows by drummers and ballad singers.

Most pilgrims, however, say they are here to “answer the call of Mother Ganges”.

A pilgrimage in which Hindus gather at points along the Ganges, Yamuna and mythical Saraswati rivers

This year’s event expects 120 million visitors over seven weeks, dwarfing last year’s Hajj pilgrimage in Saudi Arabia which drew about 2.4 million

Astrology determines most aspects of the festival, including its date, duration, and location

The most recent full Kumbh, held in 2013 in Allahabad, was also a Maha (or great) Kumbh, which happen every 144 years. It attracted an estimated 100 million visitors

A lost-and-found camp was set up in 1946 and has since helped reunite countless family members and friends who get separated in the vast crowds

This year, 15 lost-and-found camps have been set up. These computerized centers are interconnected and their announcements will be heard across the Mela grounds. Details will also be uploaded on Facebook and Twitter to help trace the missing